The strange times that we have been living in have become much stranger, and most of us have to adjust—at least temporarily—to new lifestyles, lifestyles that will reduce demands on schedules. An exception, your Editor whose life has little style at all, and none of it social, fantasizes that some of you may use the time freed up to wander through the realms of gold (apologies to Keats) that are the pages of the American Journal of Physics.
This strange moment is a particularly apt time to try out a new feature to help with that wandering: a list of “blurbs” describing the articles in the issue that follows. We are told by Wikipedia that the word originates in 1907 to honor the fictional Miss Belinda Blurb (I am not making this up), and has come to mean a short promotional statement about a creative work. AJP articles are certainly creative works, but they do not need promotion as much as they need categorization.
The obvious question is “Don't the abstracts do this?” The obvious answer is “no.” While AJP authors are experts at abstract thinking, they are not all expert at abstract writing. In their enthusiasm for the devil living in the details, they too often yield to the temptation to say too much; the abstract becomes a sort of mini-paper. A wandering reader would be better served by something that more directly answers the question “Might I be interested in reading this?” The blurbs are meant to address that question.
Although a blurbiography would help in any journal, it is so exquisitely appropriate for AJP that I fear the question why it wasn't done sooner. AJP, after all, is not just any journal, it is a journal that covers all subfields of physics, and a wandering reader might want to be sure that a target falls within the reader's aim. More importantly, AJP gold spans levels from introductory courses to advanced graduate courses. An article on “A new approach to mechanics” might preach the presentation of Newton's second law as a = F/m or might push the importance of the Hamilton–Jacobi formalism.
The reader is also served in a user-efficient way: Wandering through the table of contents, spying an article that might be of interest, our envisioned reader might sigh (oh, bother!), click on the abstract download, and endure the latency of delivery before seeing a mini-paper. What is needed is a click-free presentation of brief effective guidance. To this end, Associate Editor Joseph Romano and I present the blurbs for this issue.
A simple experimental system to illustrate the nonlinear properties of a linear chain under compression
Denis Weaire, Ali Irannezhad, Adil Mughal and Stefan Hutzler
A laboratory experiment on the percolation of a water network was developed that meets the five goals of Introductory Physics Laboratories formulated by the American Association of Physics Teachers.
The Hamilton–Jacobi equation: An alternative approach
Bahram Houchmandzadeh
The Hamilton-Jacobi formalism is typically taught as a late step in the development of canonical transformations, and its abstract nature is a barrier to appreciation. In this paper, suitable as a resource in advanced mechanics courses, the formalism is developed in a very different way that may be more intuitive.
The effects of projectile mass on ballistic pendulum displacement
James C. Sanders
A ballistic pendulum is a useful device for illustrating conservation of energy and conservation of momentum. A more careful analysis, at the introductory level, shows a non-trivial dependence of the maximum height of the pendulum on the projectile mass.
Dynamics of two freely rotating dipoles
Peter T. Haugen and Boyd F. Edwards
The motion of two freely-rotating magnetic dipoles in a plane is investigated focusing on the interesting spinning and orbital motion for two dipoles in contact. Interesting spinning and orbital motions are obtained. Though the analysis is fairly simple, it uses the Hamiltonian for the system, and so is best suited to upper level undergraduates.
Games of life
David A. Faux, Mayank Shah, and Christopher Knapp
This cross-disciplinary article, intended for undergraduates, shows the emergence of complexity in the evolution of patterns governed by simple rules. The evolution, which has some quantum aspects, is illustrated with videos.
The interplay of damping and amplitude in the nonlinear pendulum
Peter A. Braza
The pendulum is analyzed with the complications of the nonlinear (sine) restoring force combined with a linear (proportional to velocity) damping. The analysis involves only simple ordinary differential equations, and introduces useful approximation methods.
Analyzing the structure of basic quantum knowledge for instruction
Giacomo Zuccarini
This article, meant to aid instructors of quantum courses, focuses on the use of concept maps to investigate students' mental organization of quantum formal elements, and to improve that organization.
Computer-based learning in an undergraduate physics course: interfacing a mobile phone and MATLAB to study oscillatory motion
Ernesto Momox and Charby Ortega
Available sensor support for iOS and Android can be interfaced with MATLAB mobile to give students their own real-time data-taking and plotting equipment. Instructions are given and usage is discussed for the use of this article in instruction in introductory courses.
Introduction to molecular dynamics simulations
Katharina Vollmayr-Lee
This is a how-to introduction to the computing of molecular dynamics simulations, with explicit instructions in both python and the software package LAMMPS. The article is modular, requires only introductory university physics and is particularly useful for student projects.
